Diesel vehicles use similar types of emission monitors as gasoline-powered vehicles, but with some differences due to their unique combustion process. Here are some of the most common types of vehicle emission monitors for diesel vehicles: Diesel Particulate Filter (DPF): The DPF is a device that captures and stores soot particles from the diesel exhaust. It needs to be periodically cleaned through a process called regeneration to prevent it from becoming clogged and affecting the vehicle's performance. Selective Catalytic Reduction (SCR) System: The SCR system uses a urea-based solution, called diesel exhaust fluid (DEF), to reduce nitrogen oxide emissions. The DEF is injected into the exhaust stream, where it reacts with the nitrogen oxides to produce harmless nitrogen and water vapor. Exhaust Gas Recirculation (EGR) System: The EGR system in diesel engines reduces emissions by recirculating some of the exhaust gases back into the engine's combustion chamber. This helps lower the temperature of the combustion process, reducing the formation of harmful nitrogen oxides. Diesel Oxidation Catalyst (DOC): The DOC is a device that converts harmful pollutants like carbon monoxide and hydrocarbons into less harmful gases by oxidizing them. It works by using a catalyst to speed up the chemical reactions that break down the pollutants. Diesel Exhaust Fluid (DEF) Injector: The DEF injector sprays a small amount of DEF into the exhaust stream to reduce emissions of nitrogen oxides. It is part of the SCR system and is usually located in the exhaust system, close to the SCR catalyst. Overall, the type of emission monitor used in a diesel vehicle will depend on its make and model, as well as its year of manufacture. However, all modern diesel vehicles are required to have some form of emission control system to ensure compliance with emissions standards and improve overall air quality.